South Korea has approved a request by a South Korean son to visit his mother's grave in North Korea in the Moon Jae-in administration's first permission for its nationals going on a North Korean trip upon an invitation from the North, the Unification Ministry said Monday.

The ministry has accepted the request by the man surnamed Choi, a son of Ryu Mi-yong, late chairwoman of the central committee of the Chondoist Chongu Party, a North Korean minor political party.

She died of lung cancer in November 2016. Ryu and her husband, Choe Tok-sin, who served as a foreign minister in South Korea during the 1960s, emigrated to the United States before defecting to the North in 1986.

Ryu Mi-yong, late chairwoman of the central committee of the Chondoist Chongu Party (Yonhap)

"Choi's North Korean trip was approved as a humanitarian act so that he could visit his mother's grave on the first anniversary of her death," a ministry official said.

It is the first case of a South Korean individual going on a trip to North Korea at the invitation by the country since the Moon administration took power in May.

Choi is scheduled to arrive in Pyongyang via China on Wednesday and return home Saturday.